The Runner's Footprint

Our simple sport seems eco-friendly. But the truth is complicated.

A friend of mine who works in the bike industry warned me that when I got off the ferry in Shenzhen from Hong Kong, I'd notice that the place smells like glue. Fortunately, I disembark in a slightly more obscure place, Nancha, with a gleaming new terminal that looks like something you'd see in Sweden. It doesn't smell like glue, but the smog sits still in the subtropical air, and it is impossible to see the other end of the Pearl River Delta harbor. This is one of the most polluted regions of the world. A 2008 report estimates that air pollution from factories and cars is causing 10,000 premature deaths and 11 million doctor visits a year in South China, costing the economy $964 million a year.

I get picked up by Brooks's Campbell and Jorge Cabrera, VP of operations and manufacturing, who made the trip from Bothell, Washington, to oversee the manufacturing of the spring line. In a rare move, they're willing to let a reporter visit the factories where their closely guarded soles and upper materials are made and where the whole shebang comes together in an assembly line watched over by armed guards. I'm asked not to name the factories I visit. This is a competitive industry, after all.

Brooks CEO Jim Weber says the company can't assess its sustainability if it's not honest about how shoes are made. "It's not all pretty," he'd warned me before I left. "But we believe no one is working harder at it. Our belief is to be transparent. We are where we are, and we're not pretending we've figured it out."

So we pile into a minivan and lurch to a factory that makes Brooks's midsoles, what Weber calls the "engine, drive train, and chassis" of the shoe. The midsole must be all things to all people, delivering everything from durability to comfort to energy return. But if midsoles are the technical wonder of the shoe, they are also its main environmental culprit. The reason is simple: Midsoles can't last more than a couple of months under heavy use. To achieve its performance goals, a midsole (made out of a slightly varying soup of polymers generally dominated by ethylene vinyl acetate, or EVA) must sacrifice another one: its own lifespan. Like a steelhead trout, EVA can make one long glorious run before it dies belly up. Sadly, it doesn't biodegrade or make its own spawn.

Why a life so sweet and brief? The answer lies in the basic molecular construction of EVA foam. To be bouncy and light, the foam is made from a matrix of polymeric cells with entrapped gas. But running makes the foam flex and compress; over time, the walls of this matrix break down and the cells flatten out. Then you need new shoes.

"The biggest retrograde part of the shoe is the sole unit," says Aaron Azevedo, senior VP of footwear for Zoot who formerly worked at Saucony. "If you burn it or heat it, you get acrid black smoke. If you throw it in a landfill, it darn near lasts forever."

I'd heard from Patagonia footwear GM Craig Throne, who is developing trail runners, that inventing a better midsole is the Holy Grail of the industry. So far, everyone is still searching. But if it can be achieved, it could happen here, at one of the state-of-the-art foam cookeries in the Pearl River Delta.

Brooks's foam vendor-I'll call him Mr. F-is a key supplier in Asia. He makes more than a million midsoles a month and sells to many top brands, even marketing foam recipes he himself has concocted. A guardian of the secret sauces, the effervescent Mr. Foam hails from Taiwan and is a chemist as well as businessman.

According to legend, Mr. F was present at the creation of one of the biggest eco developments in recent shoe-making history: a process called Compression Molding Phylon (CMP), an advancement that halved waste and within the last few years has been picked up to varying degrees by all the big names in the industry. To help me understand it, he ushers me into a small conference room that looks a little like a kindergarten classroom. Brightly colored foam sheets lie on the floor; there's a bowl full of eggs, a bowl full of golf balls, and small vials of beads and powders lined up on a long table. The table is divided in two. On the right is the New School: the materials that go into the family recipe for the Brooks midsole. The vials hold 19 powders and pellets, including EVA, activators, lubricants, elastomers, blowing agents, curing agents, peroxides, and pigments. These will get precisely mixed and poured into a unique mold for each style and size of shoe, then heated and cooled.

On the left is the bulkier Old School: those same materials plus some others, which get made into a flat dough that is then baked into large puffy sheets, called slab EVA. These must be shrunk and cut with a giant footprint cookie cutter in a process known as die-cutting. It requires more energy and leaves a lot more waste between cutouts. Mr. F says that die-cut models still account for a decent chunk of his business, and he carts off the surplus to another factory he owns that turns the waste into car mats.

When some shoe companies say their midsole or outsole is partly recycled material, they're referring to this industrial waste. It gets reground and added to the recipe, but because it's already cooked, it lacks the properties of the raw EVA and doesn't perform as well. This, alas, is a central conundrum of making a greener shoe: The more recycled the foam, the less it rebounds and the faster it degrades. The enterprising Mr. F proudly shows me a new CMP formula he's invented called Powercushion that has a 90 percent rebound rate. "This is four years in R&D," he says, beaming. He hands me an egg, and tells me to smash it onto the Powercushion sheet.

"Really? Are you sure? Throw it?" I ask.

He nods, happy as a kid.

So I do. Sure enough, it bounces right back up like a ball.

"That's energy return!" says Mr. F.

Then he tells me to get ready for some heat, as we head for the factory floor. An EVA plant is a little like a pasta factory. The foam starts as dry raw ingredients, gets mixed, blended, rolled, pressed, cooled, and stored. We pass stockpiles of petrochemicals: large plastic bags filled with EVA resin from DuPont, stacks of greasy squares that are butyl blocks straight from Exxon and other oil giants. I think of the journey these substances have already made. The crude likely came from Nigeria, Venezuela, or Saudi Arabia, then flowed into a pipeline or tanker until it reached a refinery. Our shoes are largely made from the dregs. The "carbon black" that's often used as a toughening agent on outsoles, for example, is a by-product, leftover after the refinery extracts the "light" and favored distillates like high-octane gasoline.

When I ask Campbell how much petroleum goes into a pair of shoes, he throws up his hands. "Anyone can weigh a shoe and guess the loss of materials during manufacture," he says. "But how much petroleum is used to pump crude oil, transport it, refine it into ethylene, turn that into the different plastics, transport them, and make the components is a tough call."

Oil drives everything Mr. F and his ilk do. I'd heard that Mr. F practically had heart failure when the price of oil went to $60 a barrel. With it now topping $100, a man who has built his entire career on the slick stuff is looking for alternatives. "My final goal is to not use petroleum," says Mr. F. "Someday," he says, squeezing a cooled midsole, "this may be plant-based polymers."